[R-pkg-devel] Analysing namespace reverse dependencies

On Sat, 9 Mar 2019 at 15:07, Roger Bivand <Roger.Bivand at nhh.no> wrote:

Hi,

Is anyone aware of tools permitting the listing of functions in the
namespace of package A used by package B when package B declares that it
depends on A, suggests A, or imports(A) without specifying the functions
from A that B is using? If B imports functions from A, and uses
importsFrom() in its NAMESPACE, the information can be recovered by
inspecting its NAMESPACE file (assuming that the entries are correct), but
not otherwise.

I don't know of any specific tool, but the following function may help:

inspect_functions <- function(pkg, from) {
 regex <- paste0("(", paste(from, collapse="|"), ")::[[:alnum:]._]*")
 ns <- getNamespace(pkg)
 x <- sapply(ls(ns, all.names=TRUE), function(x) {
   f <- get(x, envir=ns)
   if (!is.function(f))
     return(NULL)
   b <- unlist(strsplit(as.character(body(f)), "\n"))
   unique(regmatches(b, regexpr(regex, b)))
 })
 x[sapply(x, Negate(length))] <- NULL
 x
}

Example:

inspect_functions("units", c("pillar", "xml2"))
#> $.read_ud_db
#> [1] "xml2::read_xml"
#>
#> $.read_ud_db_symbols
#> [1] "xml2::read_xml"     "xml2::xml_find_all" "xml2::xml_contents"
#>
#> $.ud_db_xml_list_as_dataframe
#> [1] "xml2::xml_children" "xml2::xml_length"   "xml2::xml_find_all"
#> [4] "xml2::xml_text"
#>
#> $format_type_sum.type_sum_units
#> [1] "pillar::style_subtle"
#>
#> $pillar_shaft.mixed_units
#> [1] "pillar::new_pillar_shaft_simple"
#>
#> $pillar_shaft.units
#> [1] "pillar::new_pillar_shaft_simple"
#>
#> $valid_udunits_prefixes
#> [1] "xml2::xml_children" "xml2::xml_find_all" "xml2::xml_text"
#> [4] "xml2::xml_double"

I?aki